Master cylinder for brakes



July 23, 1940. F. c. FRANK MASTER CYLINDER FOR BRAKES Original Filed June 22, 1954 4 Sheets-Sheet 1 \I/ l I we CD Fesosklck i i 9K If l BYdQWM ATTORNEY- July 23, 1940. F, FR NK 2,208,575

MASTER CYLINDER FOR BRAKES Original Filed June 22, 1934 4 Sheets-Sheet 2 /aa l' /52 A iiiii 332 IN V EN TOR.

FPEDEP/CK C. FRANK BY WA- 92.

.4 TTORNEY July 23, 1940. F, FWK V 2,208,575

MASTER CYLINDER FOR BRAKES Original Filed June 22, 1934 4 Shee ts-Sheet 5 IN V EN TOR.

FPEDEP/CK C. FPANK dgawwx 92 6 ATTORNEY.

FIG. 8'

July 23, 1940.

F. C. FRANK MASTER CYLINDER FOR BRAKES Original Filed June 22, 1954 4 Sheets-Sheet 4 INVENTOR. FPmE /c/r C. FpAA/K ATTORNEYI BY W.

Patented July 23, 1940 UNITED STATES PATENT OFFICE Application June 22. 1884, Serial No. 781,930

Renewed March 13, 1m

2 Claim (CI- 60-84..)

This application relates to hydraulic braking systems and is illustrated by a braking system particularly adapted for use with airplanes.

One of the objects of this invention is the pro- 6 vision of a braking system for airplanes which is very simple and economical to design and build.

A further object of the invention is the provision in such a system of satisfactory means for compensating for changes in the volume of the 1. liquid used therein which may arise due to leaks and changes in temperature.

A further object of the invention is the decrease in the cost of construction while attaining greater accuracy in the formation of co- 1 operating cylinders and pistons used in such systems.

A further object of the invention is the provision of means for closing a portion of the brake system whenever the airplane is in inverted pogo sition in order that the liquid being used may be prevented from flowing out.

One of the features of my invention is the provision of liners for the cylinders whereby a large portion of the machining of the cast parts of the as cylinders may be avoided.

A further feature is the design of the supporting members for the brake shoes and wheel cylinders, especially in that there is provided a brake flange arranged to be shrunk upon the axle of 30 the wheel associated therewith.

A further object is the provision of a pair of shoes connected with each other and arranged to anchor adjacent to the wheel cylinder, one of said shoes being arranged to actuate the other 35 and being itself actuated by said wheel cylinder.

Further features and objects of the invention will be apparent after a reading of the sub- Joined specification and claims and after a consideration of the accompanying drawings, in

which:

Figure 1 is a view partly ditic, partly in elevation, and partly in section illustrating my invention, but having some parts broken away for clearness:

Figure 2 is a similar view illustrating a modified embodiment of my invention; I

Figure 3 is a view in section taken substantially on the line 3-3 of Figure 2;

Figure 4 is a view in section and on an enlarged scale of a detail of Figure 2, taken substantially on the line 4-4 of Figure 2;

Figure 5 is a viewin section of a modified form of master cylinder;

Figure 6 is a view in section of another modified 55 form of master cylinder:

Figure '7 is an enlarged view in elevation of the wheel structure which is shown more or less diagrammaticallyinFigure2,somepartsbeing removed for clearness;

Figure 8isanenlarged viewinsectionof the wheel cylinder shown in Figure '1, being taken substantially on the line H of Figure 7;

Figure9isaviewsimilartol 'igure7onasomewhat smaller scale showing a modified form of wheel;

Figure 10 is a view on an enlarged scale and in section of the wheel shown in Figure 9, being taken substantially on the line llll of Figure 9; and

Figure 11 is a fragmentary view in section showing a portion of the structure shown' in Figure 9, with the axle removed.

Referring particularly to the structure shown in Figure 1, it may be seen that there is illustrated a brake pedal ll pivoted upon a rudder pedal II. The pedal I0 is connected by a link I4 with a lever I! adapted to rotate the shaft ll of the vmaster cylinder 2|. The master cylinder is provided with a partition 22 which defines a cylindrical space 24 in which the master piston 26, equipped with the sealing cup 28, is adapted to move. The shaft i8 is provided within the master cylinder III with an arm or lever ll which contacts with the piston 26 and -is thus adapted to exert pressure upon the liquid and thus to transmit pressure to the brakes.

The cylinder 14 is provided with a port 32, to which there is connected a conduit 34 leading to a wheel cylinder 38. The wheel cylinder II is mounted on a backing plate of a landing wheel 38. The wheel cylinder may be provided with a piston 40 contacting with one end of a brake shoe 42 and adapted to urge said shoe into contact with the drum 44. The shoe 4! may be connected with the secondary shoe 44, which may be pi.votally anchored at 40 adJacent to the cylinder 8 Means may be provided for replenishing the liquid maintained between the piston 20 and the piston 4!. The portion of the master cylinder 20 outside of the'partition 22 forms a reservoir in which excess liquid is normally stored. The partition 22 is provided with a compensating port such as ll through which liquid may fiow freely whenever the parts are in their normal released position, as shown.

Means may be provided for replenishing the liquid in the storage reservoir so formed in the master cylinder. To this end, I have designed a nipple II to which there may be fastened a bayonet coupling 64 provided with a shut-off valve 66 and connected by means of a flexible hose 66 with a can 60 for supplying additional liquid when required.

The system shown in Figures 2, 3, 4, 7 and 8 is similar to that shown in Figure land similar parts are designated by the same numerals with the addition of 100.

The master cylinder shown in Figures 2, 3 and 4 is formed of a casting I20 provided with a liner sleeve I22 securely fastened therein and with a piston I26. The sleeve I22 is positioned to extend vertically within the casting I20 and is provided with a slot I5I in which an arm I60 secured to the shaft I I8 is adapted to move so as to actuate the piston I26. The arm I60 is formed at "its outer end with a hole III and a pin I36 extending through said hole connects the arm with the piston I26. The casting I20 is also provided with a pair of threaded openings I62 and I64. The former is provided with a plug I66 which may be removed for the purpose of bleeding air from the apparatus. The bore I64 is provided with a bayonet coupling nipple I52 for purposes previously mentioned in connection with the description of Figure l.

The casting I20 is also formed with an opening I68 so arranged that the liner I22 may be inserted therein. This opening is normally closed by means of a plug I10, which also serves to secure the liner I22 in -the desired position. By the provision of the liner I22, the master cylinder is more easily and cheaply constructed, inasmuch as it becomes unnecessary to machine the casting so accurately as would otherwise be necessary in order that the piston I26 might fit tightly therein. It may be seen that the liner I22 is provided with a flange I26 by means of which the plug I10 secures it firmly in place.

The casting I20 is provided also with an outlet opening I12 which is connected by means of a bore I14 with a portion of the casting below the piston I26 and by means of a bore I16 with a portion of a casting forming a reservoir above the piston I26. The opening I12 is normally closed by a plug I16 formed with central bores I and I6I adapted to be connected (through a conduit such as the conduit 34) with the wheel cylinder.

By means of the arrangement, liquid pressure may be transmitted from the master cylinder t the wheel cylinders.

In order to prevent the passage of liquid from the bore I14 through the bore I16 to the space used as a reservoir, a valve I62 provided with a stem I64 is positioned to close the entrance to the bore I16. The stem I64 extends within the bore I60 and a spring I66 normally maintains the valve in contact with its seat.

The nipple I52 is provided with a pin I66 by means of which the bayonet coupling may be attached thereto. Arranged in the outer end of the nipple is a ball check valve I60 (see Figure 4).- By means of this arrangement, the liquid within the reservoir 'formed by the upper part of the casting I20 is normally maintained under atmospheric pressure and is always under atmospheric pressure when it is necessary to apply the brakes. However, when the airplane is flying in an inverted position, the ball I60 moves to close the opening at the upper end of the nipple I52 and prevents the liquid in the reservoir from flowing ou In the modified form of master cylinder shown in- Figure 5 a casting 220 somewhat similar to the casting I26 is used, but the sleeve 222 is arranged horizontally and a cap 210' is provided formed with an opening 262 adapted to be connected by a conduit with the wheel brakes. Within the sleeve 222 there is positioned a piston 226 provided with a sealing cup 226. At the forward end of said sleeve 222, there is arranged a valve 282 arranged to allow the substantially free passage of liquid forward from said master cylinder through the outlet 262. but arranged to prevent the return flow of liquid except under a pressure greater than a predetermined minimum. This valve is formed of a rubber disk 282*, a metallic cage 282', and a rubber insert 282. The cage 262 is formed with openings through which liquid may pass forward by flexing the edges of the insert 282, but through which liquid cannot pass in the return direction because the edges of the insert seal the openings. A spring 286 bears at one end upon a guide element 286 seated within the sealing cup 226 and at the opposite end bears on a flange formed upon the metallic cage 262. Thus the spring 266 maintains the cage 282 upon its seat on the, disk 282 until the pressure of the liquid returning from the brakes exceeds the pressure of the spring 286, whereupon the cage 282 is lifted from its seat on the washer 282' and liquid is allowed to escape back into the master cylinder.

The piston 226 is adapted to be actuated by an arm 230 secured to a shaft 2I6 and ports 250 and 250 formed in a support for the sleeve 222 and in the sleeve 222 itself respectively are adapted to allow liquid to flow in and out of the sleeve when the apparatus is in its normal released position in order to compensate for leakage and changes in temperature. An opening 264 is arranged for the reception of a filling nipple which, if desired, may be of the type shown in Figure 5.

In the modified form shown in Figure 6, the casting 320 is equipped with a sleeve 322 and with a piston 328 arranged within the sleeve. The piston is adapted to be actuated by an arm 330 secured to a shaft 6I8. The forward end of the master cylinder is equipped with a cap 310 having an opening 362 to which may be connected a conduit leading to the brakes. The opening 664 is arranged for the reception of a filling nipple.

The wheel and wheel brake structure of Figure 2 are shown more clearly in Figures 7 and 8. This structure is somewhat similar to the structure disclosed in my copending application Serial Number 723,789 which has issued April 21, 1936 as Patent Number 2,038,213 and the arrangement of the central cast spider formed with the integral applying cylinder and with integral arms serving to anchor the brake members, to position the brake members radially of the drum, and to determine the released position of the brake members is intended to be claimed in said copending application, as is also the combination of such a cast member with a stamped portion such as is shown more particularly in the embodiment disclosed in Figures 9, l0 and 11.

The brake generally designated I38 comprises a drum 4, brake shoes I42 and I46 and a supporting member or backing plate for the brake shoes generally designated 1.

The shoes I 42 and I46 are connected by means of an adjustable link 6. The shoe I46 is pivotally supported at one end (the upper end in Figure 7) upon the anchor I48 for the shoes as will be later more fully described. The shoe I42 is supported only by its connection with the shoe I45 and by a connection with the applying piston I45 of the hydraulic wheel cylinder I55.

The supporting member 4" comprises a light weight casting made of some suitable material such as aluminum and formed with a plurality of holes such as 4 by reason of which the casting has less weight than it would otherwise. The casting is provided with live arms each extending radially outward and designated by the numerals 425, 425, 425', 421 and 421' respectively. The am 425 carries the anchor pin I45 which extends through holes formed in yoke members 45| and 455 (as may be seen most clearly in Figure8). Asisalsoseeninsaidflgure, the web of the shoe I45 is provided with an enlarged end 455 through which the pin I45 also extends. Adjoining the yoke 45l-455, the arm 425 has formed a cylindrical shell 451 with an opening 455 in which there is positioned a stamped sleeve 4. The shell 451 together with the sleeve 4 form the cylinder I55. There is provided within the sleeve I a piston I45 carrying a rubber cup sealing member 445 on its inner face. Piston rod 441 is secured to a yoke member 445 which is fastened by a pin 45| to an enlarged portion 455 of the web of the shoe I42.

The arms 425 and 425 are provided with rollers 455 and 455* which serve to determine the released position of the brake shoes. It is to be noted that the shoe I42 has its inner surface formed with a grooved recess 451 so that the associated roller 455 may exactly determine the return position of the shoe.

The arms 421 and 421- carry pins 455 and 455 which extend through the webs oi! the associated shoes. The pins 455 and 455" are provided with spring pressed cap members such as 455 and 455' serving to determine the lateral position of the shoes within the drum.

Springs 451 and 455 serve to release the shoes from the drum when the brake applying pressure in the cylinder 455 is released.

The modification shown in Figures 9, l and 11 is similar to the structure shown in Figures '1 and 8. There is provided a drum with which there are associated brake shoes 542 and 545. The shoes are similarly connected by an adjustable link 5l5 and there is provided a cast spider 5. The spider 5" is formed with arms 525, 525, 525* and 521 and 521'. The arms 525 and 525 are provided with rollers 555 and 555" for determining the released position of the shoes and the arms 521 and 521- are provided with spring pressed steady rests 555 and 555 for determining the lateral position oi the shoes. The

arm 525 is provided with an anchor pin 545, and

a cylinder 555 cast integrally therewith. The cylinder is provided with -a piston, not shown, connected by a piston rod 541 with the applying end of the shoe 542. Dust cap 554 is also provided for the end of the cylinder. As is shown more clearly in Figure 11 the am 525 is formed with a passage way 555 through which the spring 55! extends. The shoe 545 is connected to the arm 521 by a spring 555 which together with the spring 551 connected to the upper ends of the.

together with the spider forms the backing plate for the brake.

an improved arrangement by which the various parts of the brake are secured to the wheel and to the axle may be seen most clearly in 5 Figures 9, and 11. The stub axle 555 which carries a supporting part oi. the airplane or other vehicle is formed with a plurality of integral spline elements such as 515 having radial projections 515. I provide a collar 515 formed with a 10 brake mounting flange 511 and a bearing spacer sleeve 515. The interior oi the sleeve is formed so as to complement the splines 515 and thus the collar 515 is non-rotatably secured to the stub axle 555. The casting 511 and the plate 551 are secured to the brake mounting flange 511 by bolts 5". Thus the stator members of the brake including the spider 51.1, the brake applying cylinder 555, the anchor 545 mounted on said spider,

the brake shoes 542 and 545 supported by the anchor, the cylinder 555, and the dirt protecting cover 551 are all non-rotatably secured to the stub shaft 555.

The stud shalt 555 is supported by a small diameter wheel generally designated 555. This wheel 555 is formed almost entirely in one piece, but is hollow and is formed with openings wherever possible in order to decrease the weight. Interposed between the wheel and the axle are bearings 555 and 551. The former is positioned between the edge of the sleeve 515 and a flange 555 formed as a portion of the wheel 555. The bearing 551 is positioned between a flange 55i similarly formed as a part of the wheel 555 and a nut 555 screwed upon the outer end or the shaft The wheel 555 has formed integrally therewith a drum shaped portion 555 within which there is positioned the separate drum III as a liner. The outer side of the wheel 555 is closed by a cap member 551 and a fairing plate 555.

It is believed that the operation of the struco ture disclosed would be obvious from the above description. In each or the modifications the operation is the same and the description of the operation of the structure shown in Figure 1 may be applied to all structures. Therein the operator presses upon the pedal corresponding to the pedal #5 and thus moves the master cylinder piston 25. This movement forces fluid through the conduit to the wheel cylinder and thus forces the piston outwardly to apply the shoe 42 to the drum. The movement of the drum carries the shoe around and thus applies the shoe 45 to the drum. Both shoes anchor upon the anchor 45 and the spider transmits the braking torque to the axle of the vehicle. When the braking pressure is released the springs corresponding to the springs I and 455 withdraw the shoes from their contact with the drum and the braking action is thus released.

It is to be understood that the above-described embodiments of my invention are for the purpose of illustration only and various changes may be made therein without departing from the spirit and scope of the invention.

I claim:

1. For a hydraulic mu mtem. a liquid ing a cylindrical portion, and having a passage leading from one end of the cylinder portion, a passage formed with a conical valve seat leading from a portion of the casting to connect with first named passage and the outer end 01. said second named passage being provided with a plug formed with a bore connected with the brakes, a piston movable in said cylindrical portion between the portion of the casting to which the second named passage connects and the first named passage, a shaft extending through said casting transversely of the axis of said cylindrical portion, a lever secured to said shaft and having a portion acting upon said piston, a valve interposed in said last named passageway, comprising a conical member having a stem extending outwardly from said valve seat, and a spring bearing' at one end on said plug and at the other end pressure creating device comprising a casting havof said conical valve member and surrounding said stem.

2. For a hydraulic braking system, a liquid pressure creating device comprising a casting having a cylindrical portion provided with a thin cylindrical liner, said liner extending beyond said cylindrical portion and being supported by said cylindrical portion only at the parts where pressure is exerted, a trunk piston having a head and a skirt movable in said cylindrical liner, a shaft extending through said casting transversely of the axis of said cylindrical portion, and a lever secured to said shaft and having a portion acting upon the head of said piston, the liner and the skirt of said piston being formed with a groove so that upon rotation of the lever it may extend downward into the cylindrical portion.

mnonmcxc. FRANK. 

